System for transmitting electro-radiant energy



Oct. 22, 1935. E. s. PURINGTQN 2,018,318

SYSTEM FOR TRANSMITTING ELECTRQ RADIANT ENERGY A Original Filed Dec. 23,1925 2 Sheets-Sheet l INVENTOR ELUSON S. P RlNGTON ATTORNEY Oct. 22,1935.

E. s. PURINGTQN SYSTEM FOR TRANSMITTING ELECTRO RADIANT ENERGY 2 sheetssheet 2 Original Filed Dec. 23, 1925 "w r T INVENTOR ELUSON s PUNNGTONBY u)1/W A:ITO'RNEY Patented Oct. 22, 1935 UNITED STATES PATENT OFFICESYSTEM FOR TRANSMITTING ELECTRO- RADIANT ENERGY Original applicationDecember 23, 1925, Serial No.

77,194. Divided and her 30, 1932,

5 Claims.

This invention is a division of application Serial No. 77,194, filedDecember 23, 1925, Patent No. 1,899,527, granted February 28, 1933,entitled System for transmitting electro-radiant energy.

This invention relates to radio transmission systems and particularly toan improved system 101' more efiicient transmission of radio signals.

The purpose oi this invention is to provide an efiicient transmissionsystem for wireless signalling by coupling together in a new andimproved manner two or more vacuum tubes, one or more of which may becaused to produce oscillations.

An object of this invention is to provide a simple arrangement foreffecting the modulation 01' an oscillating system.

Another object of the invention is to prevent losses in a modulatingaudion tube employed to modulate the high frequency oscillations to beradiated of a transmission system.

Another object is to provide an efilcient feedback circuit for a vacuumtube oscillator the adjustment of which is not substantiallyafifected bynor does it affect the constants of the oscillatory circuit whichdetermines the frequency of the current produced by the oscillator.

Another object of this invention is to provide a suitable circuit forby-passing any high frequency currents to keep them from the modulatortube.

Another object of the invention is to provide means for obtaining properfeedback voltage i'or the grid of a space discharge device independentof the frequency and constants of the oscillatory circuit over aconsiderable range.

Another object of this invention is to couple two oscillating circuitstogether in such a way that the frequency of one may be changed withoutatfecting the other.

Another object of this invention is to provide means whereby one of theoscillators may be of the mechanical type.

Still another object of the invention is the construction of anoscillation circuit employing a mechanical oscillator in which all thatneed be done to change the frequency generated is to replace themechanical oscillator with one 01' the proper frequency characteristics.

Still another object is to apply a radio oscillating device as a driverfor a mechanical oscillator.

Further objects will appear from consideration of the specification anddrawings in the latter of which:-

Fig. 1 is a diagram of the connections involved in an embodiment of myinvention.

Fig. 2 shows the invention as used to drive a this application Septem-Serial No. 635,492

mechanical oscillator such as a tuning fork with a series connection.

Fig. 3 shows the same with a parallel connection.

Fig. 4 shows the same with a crystal oscillator.

The embodiment of this invention illustrated in 5 Fig. 1 shows a lowfrequency or modulating oscillator l and a high frequency or radiooscillator I 2 connected by circuits so that the high frequencyoscillations produced by the radio oscillator are modulated by the lowfrequency oscillations.

The oscillating modulator triode i has connected across its anode andcathode through a condenser I on the anode side an oscillatory circuit2-3. The oscillating circuit may be keyed by means of a. key 5 connectedin circuit with a 15 condenser 6. The Irequency of oscillations producedby tube I is determined chiefly by the oscillatory circuit 2, 3 and thekeying condenser 6. Consequently the frequency 01'. oscillation isaltered by closure of the key and by this alteration l0 signalling isefiected. Instead of the keying being done by changing the capacitanceof the oscillatory circuit, it may be adapted to vary the inductance ofthe oscillatory circuit. The oscillatory circuit is connected to thecathode l in the 35 usual manner.

The plate current is supplied by a direct current generator 8 through aninductive impedance or choker coil 9. The generator is shunted by acondenser H? which will allow icy-passing of any alternating currentswhich may leak through the choke coil 9.

Grid excitation is obtained by coupling in a proper manner an inductanceI 5 connected between the grid and cathode of tube l to the in- 35ductance 2 of the oscillatory circuit 2-3. A grid leak is employed asshown in a well known manner.

The radio oscillator oi the system consists of a vacuum tube l2, theplate and filament 0! which are connected to the direct current source 8substantially in parallel with the plate and filament of the tube I. Theradio oscillator includes an oscillatory circuit which consists of aninductance l3 to which is variably connected the plate of the tube I2through a condenser H. The antenna I6 is also tapped variably toinductance [3 through a condenser l5, and the capacity to the groundindicated by H completes the oscillatory circuit.

The oscillatory circuit 2-3 of the modulating 50 oscillatoris connectedto the anode and cathode terminals 01 the radio oscillator l2, therebyplacing the two tubes in parallel relation. Connections to the anode oithe tube l2 are made through condenser I l and inductance I8.

' crystal as the case may The circuit 4-3-6 is so constructed as toprovide a capacitance path which will by-pass any and thus prevent themfrom being impressed across the modulating oscillator I. By so doing,

cited, as is done in many instances, it would not be possible to by-passall of the high frequency currents, as a condenser large enough for thispurpose could not be used without imposing aconsiderable capacitanceload on the modulator,

thereby impairing its efficiency.

As shown, grid excitation and feedback for the radio oscillator tube I2is obtained by coupling the grid to the antenna inductance 13 through atransformer, the primary of which is in parallel relation to inductancel3. The correct adjustment of the feedback is dependent only upon thefrequency at which the oscillatory circuit is to operate, so that inadjusting the transmitter to an antenna of unknown constants, the plateand wave length taps only need to be varied to produce the correctadjustment. The usual grid leak is also employed in connection with thistube.

If secrecy is desired in the transmission and reception of signals bythis systennthe low frequency must be of an inaudible frequency and thehigh frequency oscillations may be wobbled in frequency as by cyclicallyinserting condenser 23 in the oscillatory circuit in conjunction withkeying thelow frequency oscillations, making it imperative to use adouble detector system to receive the signals. A receiver suitable forreceiving under these conditions is shown in patent to Hammond No.1,540,881, June 9, 1925..

In the operation of this system, both tubes are set to oscillating, theradio oscillatory tube at a high frequency and the modulating oscillatortube at a low frequency which latter frequency will yary the amplitudeof the oscillations of the high frequency waves. The keying of themodulating oscillatory circuit changes the frequency of modulation forsignalling purposes.

It can be seen that by the arrangement shown in the drawings it ispossible by connecting a mechanical oscillation device such as a tuningfork or a piezo-electric crystal in place of the cs- 1) and coupling thecircuit to the grid circuit that an oscillation generatorcircuit willresult which is capable of generating oscillations of a frequencydependent over a considerable range mechanical oscillator device only sothat all that need be done inorder to change the frequency to upon thefrequency of the be generated is to change the tuning fork or the be.Putting it another way, there-will be a negative resistance developedacross the winding 2 or across the anode cathode of the tube such thatif a: mechanical oscillator is placed across either, of said pointsenergy of a frequency equal to the frequency of themechanical'oscillator-will be generated. Thus, the same principles ofcoupling'the grid for the purpose of excitation and feedback by means-ofthe transformer connection can be applied to series or parallel circuitsto drivers of mechanical oscillators. Three such arrangements are shownin Figs. 2 to 4. V V

More particularly in Fig. 2 there is shown.

.means for electrically controlling a thermionic radio frequencycurrents produced by the tube I2 valve by means of a tuning fork. Thethermionic device 30 includes in its plate circuit the coil 3| of thedrive of the tuning fork 32 and the high potential source 33 and the{plate circuit is shunted by the circuit composed of the condenser 5 34and inductance 35, the latter of which is inductively coupled to theinductance 33 in the grid circuit of said thermionic device. The platecurrent serves to actuate the tuning fork ,by means of theelectro-magnet formed by the inductance 10 3| and the core 38 as shown,and the oscillating current existing in this circuit is fed back to thegrid circuit by means of the inductive coupling between the inductances35 and 33. Should the oscillations existing in the plate circuit andcon- 15 sequently in the electro-magnet be opposed to the natural motionof the tuning fork, a second electro-motive-force will be generatedwhich will in passing through the condenser 34 influence the inductance35in such a manner as to impress a 20 potential tance 40 and the highpotential source 33. The 30.

grid circuit includes the grid and the inductance 36. In shunt with theplate circuit is a second plate circuit including a condenser 34 and theinductance 35, the latter of which is inductively 7 related to the gridinductance 36. In parallel with 35 the inductance 35 is theelectro-magnetic winding 43 of the tuning fork 32. The vibration of thetuning fork will impress upon the electro-magnetic winding a frequencywhich is the same as the natural frequency of the tuning fork and thiswill cause a current to flow through the inductance 35 which will causea current to be impressed upon the grid inductance 36 in such a manneras to cause the plate current to vary through the action of the device30 in accordance with the frequency of the tuning fork. The platevoltage will be transferred by means of a condenser 34 to the tuningfork inductance 43 and will serve to augment the current in the tuningfork circuit provided it is in phase therewith. I In case the naturalfre- 5 quency of the oscillatory circuit is not the same as the naturalfrequency of the tuning fork, the current generated by the latter willbuck that generated by the former and the phase. of the input of thewill be shifted until the output of the said device will aid theelectro-motive-force generated by the tuning fork. .Thus, it can be seenthat the tuning fork can be made to control the frequency of thethermionicdevice 30. larly it may be seen that in either Fig. 2 or 3, ifthe current produced by the tuning fork 32 and the current produced bythe thermionic device 30 are in phase an oscillatory E. M. F. will befurnished to the tuning serve to keep the fork 32 in motion.

Referring now more particularly to Fig. 4 there is shown a system forcontrolling the oscillation of the thermionic circuit by means of apiezo crystal.

7 The connections of the thermionic device are the 70 thermionic device30 Simiw fork inductance which will frequency of the thermionicoscillator is the same as that of the tuning fork in Fig. 3. In otherwords, as long as the electro-motive-force in the inductance 35 causedby the transfer of ener y from the plate circuit through the condenser34 is in phase with the electro-motive-iorce generated by the vibrationof the piezo crystal, the frequency of the impulses impressed on thegrid of the thermionic device 30 will remain constant.

It is evident from what has preceded that the frequency generated by anyof the three circuits is for a considerable range dependent only uponthe frequency constants of the mechanical oscillation so that should adifferent frequency be required all that need be done when my system isutilized is to change the tuning fork or the piezo crystal. This is adistinct advantage over the systems now in use with plug in coils sincein such systems the tickler coil must be changed as well as the tuningcoil.

The invention is not limited to the above uses which are describedmerely as illustrations, but on the other hand may be utilized in manyways as will be defined in the appended claims.

I claim:

1. An oscillation generator comprising an electronic oscillator havingan anode, a. cathode and a grid, a circuit connection between said anodeand cathode including a choke coil and a source of space current, asecond circuit connected between said anode and cathode including acondenser and a coil, a circuit for connecting the grid and cathodeincluding a coil, said two coils being inductively related so as toeffectively couple said second circuit and said last named circuit, anda circuit including resonator driving means shunted across said firstcoil, a resonator adapted to be driven thereby and. to induce electricalactions in said circuits ior determining the frequency of the producedoscillations.

2. An oscillation generator comprising an electronic tube having ananode, a cathode and a grid, a circuit connection between said anode andcathode including a source of space current, a second circuit connectedbetween said anode and cathode including a coupling coil, a circuit forconnecting the grid and cathode including a coiL'said two coils beinginductively related so as to effectively couple said second circuit andsaid last named circuit, a resonator driving means in one of said firsttwo named circuits and shunted across at least the first named coil, aresonator adapted to be driven thereby and to induce electrical actionsin said circuits for determining the frequency of the producedoscillations.

3. In a circuit arrangement for generating oscillations 01' anyfrequency within predetermined limits the frequency of the generatedoscillations 5 being determined solely by the characteristics of aresonator device, an electronic tube including an anode, a cathode and agrid electrode, a connection between the grid electrode and cathodeincluding the secondary winding of a coupling 10 transformer, aconnection between the anode and cathode of said tube including acondenser and the primary winding of said coupling transformer inseries, a resonator device and driving means therefor and a connectionacross said condenser 15 and primary winding including said resonatordriving means and a source of space current for said tube in series.

4. In a circuit arrangement for generating oscillations of any frequencywithin a band of 20 frequencies of substantial width, and wherein thefrequency of the generated oscillations is dependent only upon theirequency characteristics of a resonator device, an electronic tubeincluding an anode, a cathode and a grid electrode, a 25 connectionbetween the grid electrode and cathode including the secondary windingof a coupling transformer, a connection between the anode and cathode ofsaid tube including a condenser and the primary winding of said coupling30 transformer in series, a resonator device and driving means therefor,a connection across said condenser and primary winding including asource of space current for said tube and a connection across saidprimary winding including said res- 35 onator driving means.

5. In a circuit arrangement for generating oscillations of any frequencywithin predetermined limits, the frequency of the generated oscillationsbeing determined solely by the characteristics of so a resonator device,an electronic tube including an anode, a cathode and a grid electrode, aconnection between the grid electrode and the oathode including one ofthe windings of a transformer, a connection between the anode and 45cathode of said tube including a condenser and the other winding of thetransformer in series,

a resonator device and driving means therefor and a connection acrosssaid condenser and the first mentioned winding including said resonator50 driving means and a source of space current for said tube in series.

ELLISON S. PURINGTON.

